The use of cellular phones and other types of wireless communication devices (WCDs) is becoming increasingly prevalent and popular in modern life. To provide cellular wireless communication service to such WCDs (also often referred to as client devices, user equipment, mobile stations, subscriber devices, access terminals, and the like), a wireless service provider typically operates a radio access network (RAN) that defines coverage areas (e.g., cells, sectors, and the like) in which subscribers' WCDs can be served by the RAN and obtain connectivity to other networks such as the public switched telephone network (PSTN) and the Internet.
A typical RAN includes one or more base transceiver stations (BTSs), each of which may radiate to define one or more coverage areas in which these WCDs can operate. Further, the RAN may include one or more radio network controllers (RNCs) or the like, which may be integrated with or otherwise in communication with the BTSs, and which may include or be in communication with one or more switches and/or gateways that provide connectivity with one or more transport networks. Conveniently, with this arrangement, a WCD that is positioned within the coverage of the RAN can communicate with a BTS and in turn with other served devices and/or with other entities via the one or more transport networks.
In each coverage area, a RAN will typically broadcast (via, e.g., a BTS) a pilot signal that among other purposes notifies WCDs of the presence of the coverage area. In operation, when a WCD detects a pilot signal of sufficient strength, the WCD may transmit what is known as a registration message to the RAN to notify the RAN that the device is in the coverage area, and the device may then operate in the coverage area in what is typically known as “idle” mode. When operating in idle mode, the WCD is not actively engaged in a call or other traffic (e.g., packet-data) communication, but does regularly monitor overhead signals in the coverage area to obtain system information and page messages, as examples.